A sample is analyzed to determine its iron content Fe2+ via a redox titration with potassium chromate as the titrant. In the titration Fe2+ is oxidized to Fe3+ and CrO4 2- is reduced to Cr 3+. What is the percent by mass of iron in the sample if 0.9087g of the sample required 45.68mL of a 0.04322 M K2CrO4 solution to reach the endpoint?

I worked out the balanced equation to be:

8H+ + 3Fe2+ + CrO4 2- = 3Fe3+ + Cr3+ + 4H2O

What is the mechanism by which solute is dissolved in non polar solvents? Explain briefly. (5 mark)

Part B What mass of carbon dioxide is produced from the complete combustion of 6.90×10−3 g of methane? Express your answer with the appropriate units.

Part C What mass of water is produced from the complete combustion of 6.90×10−3 g of methane? Express your answer with the appropriate units. Part D What mass of oxygen is needed for the complete combustion of 6.90×10−3 g of methane? Express your answer with the appropriate units   

The equilibrium constant for the reaction of fluorine gas with bromine gas at 300 K is 54.7 and the reaction is: Br2(g) + F2(g) ⇔ 2 BrF(g) What is the equilibrium concentration of fluorine if the initial concentrations of bromine and fluorine were 0.121 moles/liter in a sealed container and no product was present initially?

In each pair, indicate which substance has the stronger intermolecular forces and explain your reasoning: (a) Ne, Ar; (b) NF3, BF3; (c) SiH4, GeH4; (d) NaF, HF.

1. Calculate the dilution factor and final concentration of the following target analytes:

20 mL of target analyte (2.5 M), to a final volume of 100 mL

2 mL of target analyte (3.23 ppm), to a final volume of 0.05 L.

5 mL of target analyte (15.9032 %), to a final volume of 1 dL.

1 dL of target analyte (4.0989 M), to a final volume of 0.25 L

0.025 L of target analyte (1.8982 g / L), to 79 g of ethanol.

10 mL of target analyte (2.0902 g / L), to 66.5 g of dichloromethane.

A solution containing a mixture of metal cations was treated with dilute HCl and a precipitate formed. The solution was filtered and H2S was bubbled through the acidic solution. A precipitate again formed and was filtered off. Then, the pH was raised to about 8 and H2S was again bubbled through the solution. This time, no precipitate formed. Finally, the solution was treated with a sodium carbonate solution, which resulted in formation of a precipitate. Which metal ions were definitely present, which were definitely absent, and which may or may not have been present in the original mixture? Ag+, Zn2+, Co2+, Li+, Cu2+, Ca2+, Fe2+, Sn2+, Mg2+, Hg22+ Sb3+, Hg2+, Pb2+

1. Add the periodic trend of electronegativity to your periodic table.
2. On your periodic table underline the elements that make up the 7 diatomic molecules (from chapter 6.6) and add the periodic trends of ionization energy, atomic size, and metallic character (chapter 4.8).

Please explain...

In the titration of a weak acid HA with 0.100 M NaOH, the stoichiometric point is known to occur at a pH value of approximately 11. Which of the following indicators would be best to use to mark the endpoint of this titration?

a. an indicator with Ka = 10–13

b. an indicator with Ka = 10–14

c. an indicator with Ka = 10–10

d. an indicator with Ka = 10–8

e. an indicator with Ka = 10–11

An indicator HIn has Ka = 1 × 10–8. At pH = 6.0, what is the ratio HIn/In– ?

a. 1/100

b. 10/1

c. 1/1

d. 100/1

e. none of these

balance redox reaction that occurs in acidic conditions. what are coefficients for H + & Fe3+ once reaction is balanced? write it as H+=#; Fe +3 = #

Fe2+(aq)+Mn04-(aq) -> Fe3+(aq)+Mn2+(aq)

1. Ph of H3O+ of 5.7x10^3
2. Ph of a 1.5x10^-2 m for HBr

3. ph of 3.24x10^-4 m of hypochlorous acid ka2.9x10^-8

In organic chemistry, we have ortho/para activators and deactivators. Why do we not have meta activators?

Indicate the concentration of each ion present in the solution formed by mixing the following. (Assume that the volumes are additive.)

(a) 40 mL of 0.100 M HCl and 10.0 mL of 0.600 M HCl

H⁺ ________ M

Cl ^- ________ M


(b) 15.0 mL of 0.300 M Na₂SO₄ and 20.6 mL of 0.200 M KCl

Na⁺ _________ M

K⁺ __________ M

SO₄^2- __________ M

Cl ^- __________ M


(c) 3.50 g of NaCl in 40.6 mL of 0.365 M CaCl₂ solution
Na⁺ ___________ M

Ca²⁺ __________ M

Cl ^- __________ M

Calculate the hydronium ion concentration and the pH when 65.0 mL of 0.45 M NH3 is mixed with 65.0 mL of 0.45 M HCl (Ka = 5.6x10^-10).

Concentration =

pH=